1. Technical Field
The present invention relates to an image forming apparatus, and a security printing method for an image forming apparatus.
2. Background Art
Security printing that prints a user name, printed time, and a matrix type two-dimensional code compulsory on sheets such as transfer sheets is known. By compulsory printing the user name, printed time and matrix type two-dimensional code as a stamp on document sheets having high security level, taking out of high-security level document by printing the documents can be prevented.
Further, post-processing after printing such as double copy and double punching is known. The double copy means printing one same image on each of two areas on one sheet by divining the one sheet into the two areas. The double punching means process of perforating punch holes at two portions of a printed sheet, and then the punched sheet is cut into two sheets so that the two sheets can be used independently. By using these functions, an amount of sheets can be saved and printing cost can be reduced.
The above mentioned post-processing is followed by a process of cutting the sheet after the printing. Therefore, when the post-processing is combined with the security printing, security printing may not be conducted on one of the cut sheets, and thereby security printing effect cannot be obtained for the cut sheet.